Conventional methods for curing concrete may be roughly classified as follows:
(a) Moist curing, PA1 (b) Steam curing, and PA1 (c) Membrane curing. PA1 (1) It is neutral and not corrosive to concrete. PA1 (2) Its moisture loss rate is small so that enough water is provided for the hydration and setting of cement for better concrete strength, earlier setting time and sound appearance. PA1 (3) There is no need to spray water on the cured concrete within one month after being treated with the present curing agent so that labor cost may be saved in the construction project. PA1 (4) The setting time of concrete is shortened by using the present curing agent to prevent hydrolysis of concrete when impregnated in the water.
For moist curing, the concrete should be always supplied with water. If the water is not supplied continuously, the intermittent moistening and drying effect may crack the concrete surface. If water floods on the concrete surface in a long period, it may corrode or erode the concrete because of the impurities or corrosives contained therein.
The steam curing method is generally applied to make precasting concrete as in mass production. It is not suitably applied for curing concrete for buildings, roads, airport runways and other concrete construction in large areas.
Regarding membrane curing method, a sealing compound is always used to form a membrane on the concrete surface to prevent moisture loss. Conventional sealing compounds such as white paint comprising oil, wax, resin and fine paint powder may be used. However, it will be deteriorated by exposure to the weather to form spots on the concrete surface so that the concrete appearance will be contaminated. If water-soluble asphalt or oil-soluble asphalt is used as the sealing compound, it may absorb solar heat to increase expansion and shrinkage effects which will cause cracks on the concrete surface.
Another recently developed curing agent has included a drying agent which will increase the total production cost and may affect the product quality as residue is released from said drying agent.